I went ahead and put the motor together yesterday. Well most of it that is. Vespa motors are pretty simple compared to most. The only Vespa specific tools I have used are the clutch socket and the flywheel puller. Oh yeah, the crank puller Al made for me.
The reassembly went pretty easy. My 7yo son decided to jump in and help for a couple hours. Yes, he actually did install the layshaft and the needle bearings.... He preferred any job that allowed him to play with the grease. Saw a great assembly tip from the Cockspeed tuning guys on YouTube. After putting all the needle bearing in grease around the shaft, put a small zip tie around them to hold them in place. When you tap the layshaft in, the zip tie just pops off and all the bearing stay put.
http://www.youtube.com/watch?v=vw8uW-gD3Us 2:15 in
Here is a shot with the new crank in place. The puller made the job easy. Just make sure to align a cut area of the crank with the rotary pad as you pull the crank in. It may not go in 100% straight to start and you don't want to risk shaving metal from the rotor pad. Hotrod Al told me a have the first of his new crank designs. It has the inlet timing modified by cutting the counterweight in both directions. The goal is to increase the inlet timing and reduce the blow-back at low RPM.
I actually got a little farther than this. I stopped at this point and cleaned everything up. I couldn't leave well enough alone so I installed the rear brake, airbox and stator after dinner.
I went ahead and put the piston, cylinder and head on and went about measuring the squish clearance. I knew it was big but figured there was no point in trying to correct it till I put in the new crank. I am shooting for about 1.2mm. The clearance is running about 1.8mm. I am going to fire the head off to Al and have him cut 0.6mm from the surface prior to final assembly.
While I was at it, I decided to double check all the port timing numbers on the motor. I used the same TDC setup as before and printed out a degree wheel and made a pointer out of a piece of coat hanger. I used a magnet to hold the degree wheel to the end of the crank (thanks Dave at ScooterMercato).
Here are the actual timing numbers from the motor for those who are curious...
Exhaust Opening - 91deg ATDC
Exhaust Duration - 178deg
Transfer Opening - 117deg ATDC
Transfer Blowdown - 26deg
Boost Port Opening - 121 deg ATDC
Intake Opening - 115deg BTDC
Intake Closing - 61deg ATDC
Intake Duration - 176deg
Chuck
Last edited by chuckactor on Sat, 28 Jan 2012 18:49:58 +0000; edited 2 times